US20100047088A1

US20100047088A1 - Roller vane pump with integrated motor

Info

Publication number: US20100047088A1
Application number: US12/194,658
Authority: US
Inventors: Jerry L. Martin
Original assignee: Protonex Technology Corp
Current assignee: Ballard Unmanned Systems Inc
Priority date: 2008-08-20
Filing date: 2008-08-20
Publication date: 2010-02-25

Abstract

A pump includes a housing with an inlet and an outlet, and a stator that generates a rotating magnetic field and defines a pumping chamber. A rotor mounted for axial rotation within the pumping chamber has salient poles to interact with the field. The rotor mounts eccentrically such that a gap between the rotor body and stator varies circumferentially. The rotor defines hollows intermediate the salient poles with cylindrical rollers for free radial movement therein. Fluid-filled volumes are formed between the housing, the rotor and the rollers. On each side of a plane passing through the rotor axis and the housing axis, the pumping chamber is in fluid communication with the inlet or outlet, respectively. The volume expands on one side of the plane and contracts on the other. As the rotor spins, the expanding volume draws fluid from the inlet and the contracting volume expels fluid from the outlet.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The subject invention is directed to a roller vane pump driven by an electric motor, wherein the rotor assembly of the electric motor also serves to pressurize the working fluid.
2. Description of Related Art
Pumps are well known in the art, and have been employed in a wide variety of application for many years. Most pumps utilize a motor to drive a drive shaft with a rotary impeller mounted thereon. Typically, large housings are required to contain the separate components. Pumps for the aerospace industry, fuel cell applications and the like must be designed with cost, size, weight, complexity, performance and durability requirements in mind.
In an effort to simplify pump design, U.S. Pat. No. 6,109,887, the disclosure of which is herein incorporated by reference in its entirety, has added a blade to a rotor to push the working fluid. The overall pump in U.S. Pat. No. 6,109,887 is still relatively large as a blade was simply added onto a traditional rotor. In view of the above, there is a need for an improved pump that has parts which serve multiple functions to simplify design and decrease the overall profile.

SUMMARY OF THE INVENTION

Pumps in accordance with the subject disclosure have numerous applications such as fuel cells or as a cooling pump for a spacecraft, avionics equipment or for computers and high-power electronics. Such pumps are miniature and can pump fluids in pumped two-phase electronics cooling loops and be used for any applications requiring a small pump.
The subject disclosure is directed to a roller vane pump assembly including a housing defining an interior, at least one inlet for admitting fluid in and at least one outlet for allowing fluid out of the interior. A stator assembly is within the interior and has a stator and windings for generating a rotating magnetic field. The stator assembly defines a pumping chamber within the interior. A rotor assembly mounts for axial rotation within the pumping chamber, the rotor assembly including a body having salient poles to interact with the rotating magnetic field. The body also defines a plurality of hollows intermediate the salient poles, wherein the rotor assembly is mounted eccentrically with respect to the pumping chamber such that a gap between the rotor body and pumping chamber varies circumferentially.
A plurality of cylindrical rollers are disposed in the hollows for free radial movement within the hollows. Fluid-filled volumes are formed between the housing interior, the rotor body and the rollers. On each side of a plane passing through the rotor axis and the housing axis, the pumping chamber is in fluid communication with an inlet or outlet. As the rotor body spins due to the rotating magnetic field, the fluid-filled chambers expand on one side of the plane and contract on the other side of the plane. The expanding volumes draw fluid from the inlet and the contracting volumes expel fluid from the outlet.
In a further embodiment, the stator assembly further comprises a filler material that defines the pumping chamber and secures the stator assembly in place. Alternatively, the stator assembly further comprises a wall for defining the pumping chamber. The rotor assembly may include a permanent magnet coupled to each projection or be fabricated from a magnetic material.
It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, and a method for applications now known and later developed. These and other features of the system disclosed herein will become more readily apparent from the following description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject invention appertains will readily understand how to make and use a vane pump of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail below with reference to the following figures.

FIG. 1 is an exploded perspective view of a vane pump assembly of the subject disclosure with a rotor that works the fluid.

FIG. 2 is an end view with the end cap removed from the pump assembly of FIG. 1 to illustrate the pumping pockets and eccentricity of the rotor assembly with respect to the stator assembly.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The advantages, and other features of the technology disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred embodiments taken in conjunction with the drawings which set forth some representative embodiments of the present invention. All relative descriptions herein such as 12 o'clock, 6 o'clock, front, rear, side, left, right, up, and down are with reference to the Figures, and not meant in a limiting sense.
Referring now to FIG. 1, an exploded perspective view of a vane pump assembly 10 in accordance with the subject disclosure is shown. In brief overview, the pump assembly 10 is a roller vane pump with an electric drive motor contained within a housing 20. The housing 20 includes a stator assembly 30 and a rotor assembly 40 that combine to form a permanent-magnet, brushless DC motor. The rotor assembly 40 serves combined duty as a rotor of the electric motor and as the fluid working element of the roller vane pump.
The housing 20 of the pump assembly 10 serves as an outer pressure boundary and includes front and rear end caps 22 a, 22 b. The front and rear end caps 22 a, 22 b are separated from one another by an annular spacer 24. The end caps 22 a, 22 b and annular spacer 24 sealingly couple together to form an interior or sealed chamber 25 of the housing 20. The front and rear end caps 22 a, 22 b may include a circular shoulder 23 only shown on rear end cap 22 b.
As shown in FIG. 1, the front end cap 22 a maybe integrally formed with the annular spacer 24. The annular spacer 24 and end caps 22 a, 22 b may be joined by any means capable of minimizing fluid leakage from the resulting housing 20. Such means are well known to those skilled in the art, and include welding, brazing, adhesive joining, bolting, and combinations of such methods. Both end caps 22 a, 22 b may also be formed individually or integrally with the housing 20.
An inlet port 26 a and an outlet port 26 b are formed in the respective end caps 22 a, 22 b. In a preferred embodiment, there may be multiple inlet and outlet ports formed separately, in the annular spacer 24 or in a single end cap 22 a, 22 b. The inlet port 26 a admits low pressure fluid into the pump assembly 10. By passing through the pump assembly 10, the low pressure fluid becomes pressurized and exits by the outlet port 26 b.
At least one of the end caps 22 a, 22 b forms an axial passageway 27 through which an elongated shaft 45 passes to attach to the rotor assembly 40. Bearings 46 mount between the shaft 45 and the housing 20, and/or between the shaft 45 and the rotor assembly 40 to reduce friction. The rotor assembly 40 is mounted on the shaft 45 for axial rotation within the housing 20. The rotor assembly 40 rotates about a first central axis or rotor axis 42 (see FIG. 2) passing substantially centrally through the shaft 45. One or more seals (not shown) may be provided to reduce leakage about the axial passageway(s) 27 and between the annular spacer 24 and end caps 22 a, 22 b.
The stator assembly 30 is also inside the housing 20 and surrounds the rotor assembly 40. The stator assembly 30 includes a stator 31 and associated windings 32. A control circuit (not shown) provides current to the stator windings or coils 32 to generate a rotating magnetic field. The magnetic field drives the rotor assembly 40. The current to the stator windings 32 may be switched such that the stator and rotor assemblies 30, 40 function as a brushless DC motor in a manner known to those skilled in the art. Alternative embodiments may include, without limitation, synchronous AC motors, switched-reluctance motors and stepper motors.
Referring additionally to FIG. 2, an end view with the front end cap 22 a removed from the pump assembly 10 of the subject disclosure illustrates the eccentricity of the rotor assembly 40 with respect to the stator assembly 30. The rotor assembly 40 has a generally cylindrical rotor body 44 that includes a plurality of projections 41 extending radially therefrom. The rotor body 44 may be a soft magnetic material, a composite of magnetic materials, a non-magnetic material with permanent magnets, or combinations thereof so that each projection 41 is a salient pole of the electrical drive motor. The rotor body 44 also defines elongated semi-oblong hollows 47 intermediate adjacent projections 41.
In the embodiment of FIGS. 1 and 2, the rotor body 44 is comprised of magnetic material and the projections 41 form alternating North (N) and South (S) magnetic poles for a total of six poles. In a preferred embodiment, the rotor body 44 has an even number of projections 41 and the corresponding stator assembly 30 has a number of windings 32 divisible by three (e.g., nine as shown), which are driven with a three-phase current. As a result, the stator assembly 30 and the rotor assembly 40 form a brushless DC motor. The number of stator windings 32 and rotor projections 41 as well as the respective shapes, sizes, materials and strengths can be selected in accordance with known principles of electric motor design to obtain the desired torque and speed of the pump assembly 10.
Still referring to FIGS. 1 and 2, the stator assembly 30 defines an inner bore 35 in which a generally cylindrical pump chamber wall 60 is located around the rotor assembly 40. The pumping chamber wall 60 is centered about a second central axis or housing axis 43 offset with respect to the first central axis 42. Thus, the rotor assembly 40 is mounted eccentrically within the pumping chamber wall 60. The end caps 22 a, 22 b, pumping chamber wall 60, stator assembly 30 and the rotor assembly 40 combine to form a pumping chamber 70 best seen in FIG. 2. The circular shoulder 23 of the rear end cap 22 b fits partially within the pumping chamber wall 60 to limit flow out of the pumping chamber 70 and the front end cap 22 a may have a similar structure.
In one embodiment, the pumping chamber wall 60 is formed as part of one side of the housing 20. In another embodiment, the pumping chamber wall 60 is a thin sleeve that is inserted into one part of the housing 20 before the stator assembly 30 is potted in place with plastic or epoxy.
Referring to FIG. 2, the area 74 surrounding the pumping chamber wall 60 and within the housing 20 maybe filled with a filler material 61 to reduce the fluid volume inside the housing 20 and/or prevent fluid from contacting the stator assembly 30. Additionally, the filler material 61 may act to secure the stator assembly 30 and/or the pumping chamber wall 60 in place. The filler material 61 is selected to be compatible with the fluid being pumped.
In another embodiment, the pumping chamber wall 60 is not a separate component from the filler material 61. In other words, the filler material 61 is formed to create a cylindrical surface surrounding the rotor assembly 40. For example, to form the cylindrical surface from the filler material 61, a temporary plug (not shown) is placed into the pumping chamber 70. The space between the housing 20 and the plug is filled with a plastic or epoxy material, in this way creating the cylindrical surface or wall as an integral part of the plastic or epoxy potting compound for the stator assembly 30. After the epoxy or potting compound has sufficiently cured, the plug may be removed.
A cylindrical roller 50 is disposed in each hollow 47 intermediate the salient poles or projections 41 of the rotor body 44. The rollers 50 are free to move within the hollows 47 but radially retained therein by the pumping chamber wall 60. The rollers 50 may be comprised of plastic, metal, ceramic or combinations thereof. Plastic rollers 50 filled with low-friction material are particularly advantageous, as such rollers have low density and low coefficients of friction, minimizing the frictional losses in the pump assembly 10.
As a result of the eccentricity between the rotor assembly 40 and the pumping chamber wall 60, the space 72 between the pumping chamber wall 60 and the projections 41 of the rotor body 44 varies. The position of the rollers 50 in the respective hollow 47 also varies depending upon the rotational position of the rotor body 44. Consequently, the volume between the rotor body 44, the pumping chamber wall 60 and adjacent rollers 50 varies depending upon the rotational position of the rotor body 44.
In operation, the windings 32 of the stator assembly 30 are energized in sequence to provide a rotating magnetic field. The magnetic field interacts with the salient poles or projections 41 to rotate the rotor assembly 40. Fluid-filled volumes 71 are formed between the housing interior 25, the rotor body 44 and the rollers 50. On each side of a plane 49 passing through the rotor axis 42 and the housing axis 43, the pumping chamber 70 is in fluid communication with the inlet 26 a or outlet 26 b, respectively. As the rotor body 44 spins due to the rotating magnetic field, the fluid-filled volumes 71 expand on one side of the plane 49 and contract on the other side of the plane 49. The expanding volumes 71 draw fluid from the inlet 26 a and the contracting volumes expel fluid from the outlet 26 b.
For example, assume that the rotor body 44 rotates clockwise in FIG. 2 although the subject technology is not so limited. Between approximately the twelve o'clock position and the six o'clock position in FIG. 2 (e.g., the right side of the plane 49), the space 72 and the volumes 71 increase with the centrifugal force spinning the rollers 50 radially outward. The increased volumes 71 create a suction effect, which draws fluid from the axial end of the pump assembly 10 through the inlet port 26 a into the pumping chamber 70.
As the rotor body 44 continues to spin clockwise, the space 72 and the volumes 71 between the six o'clock and twelve o'clock positions decrease (e.g., the left side of the plane 49), expelling fluid from the outlet port 26 b. If the rotor body 44 spins counterclockwise, fluid is drawn into the port 26 b and expelled from the port 26 a. Therefore, the pumping direction may be reversed by reversing the direction of rotor assembly rotation.
In view of the above, the rotor body 44 provides a plurality of volumes 71, partially defined by the varying space 72, which combine to pressurize the low pressure intake fluid. The rotor body 44 also provides projections 41 that act as salient poles, which are a component of the electrical drive motor. Thus, a drive mechanism separate from the component that works the fluid is not required. Such a pump assembly 10 can be miniaturized for applications requiring a small pump because of the dual function of the rotor assembly 40. Additionally, the pump assembly 10 has the rotor assembly 40 and optionally the stator assembly 30 immersed in fluid which may provide cooling for the electrical drive motor of the pump assembly 10.
It is to be appreciated that the subject disclosure includes many different advantageous feature, each of which may be interchanged in any combination on like pump assemblies. While pump assemblies of the subject invention have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications may be made thereto without departing from the spirit and scope of the subject invention as defined by the appended claims.

Claims

1. A roller vane pump assembly comprising:

a) a housing defining an interior, at least one inlet for admitting fluid in and at least one outlet for allowing fluid out of the interior;

b) a stator assembly within the interior having a stator and windings for generating a rotating magnetic field, wherein the stator assembly defines a pumping chamber about a stator axis within the interior;

c) a rotor assembly mounted for rotation about a rotor axis within the pumping chamber, the rotor assembly including a body having projections that act as salient poles to interact with the rotating magnetic field, the body also defining a plurality of hollows intermediate the projections, wherein the rotor assembly is mounted eccentrically with respect to the pumping chamber such that a plane substantially passing through the rotor and stator axis defines first and second sides of the body; and

d) a plurality of cylindrical rollers, each roller disposed in a respective hollow for free radial movement within the hollow,

wherein as the body spins due to the rotating magnetic field, volumes between adjacent rollers, the rotor assembly and the pumping chamber expand on the first side of the rotor drawing fluid from the at least one inlet and contract on the second side expelling the fluid from the at least one outlet.

2. A vane pump assembly as recited in claim 1, wherein the stator assembly further comprises a filler material that defines the pumping chamber and secures the stator assembly in place.

3. A vane pump assembly as recited in claim 1, wherein the stator assembly further comprises a wall for defining the pumping chamber.

4. A vane pump assembly as recited in claim 4, further comprising a permanent magnet coupled to each projection.

5. A vane pump assembly as recited in claim 1, wherein the body is a magnetic material.

6. A vane pump assembly as recited in claim 6, wherein the body has six projections and six hollows, and the stator assembly has nine windings.

7. A vane pump assembly comprising:

a) a cylindrical pumping wall having an inner circumferential surface defining a pumping chamber;

b) a rotor assembly eccentrically mounted with respect to the cylindrical pumping wall for axial rotation, the rotor assembly having a rotor body defining a plurality of circumferentially spaced apart radially extending vane pockets intermediate projections, each projection being magnetic;

c) a cylindrical roller supported in each radially extending vane pocket;

d) a stator assembly surrounding the cylindrical pumping wall and having windings for generating a magnetic field to act upon the projections; and

e) a housing surrounding the stator assembly and defining inlet and outlet ports for ingress and egress of fluid.

8. A vane pump assembly as recited in claim 7, wherein the rotor body has six projections and six vane pockets and the stator assembly has nine windings.

9. A vane pump assembly as recited in claim 7, wherein the cylindrical pumping wall includes a closed end and an open end, which has been sealed to the housing to form a pressure boundary about the rotor assembly and within the stator assembly.

10. A vane pump assembly as recited in claim 9, wherein the open end of the cylindrical pumping chamber has a flange that is hermetically sealed to an annular groove formed in an inner face of the housing.

11. A vane pump assembly as recited in claim 7, wherein the stator assembly further comprises a filler material that secures the stator assembly in place.

12. A vane pump assembly as recited in claim 7, further comprising a permanent magnet coupled to each projection.

13. A vane pump assembly as recited in claim 1, wherein the rotor body is a soft magnetic material.

14. A roller vane pump assembly comprising:

b) a stator with windings in the interior for generating a rotating magnetic field, the stator having a wall defining a pumping chamber;

c) a rotor body mounted for axial rotation within the pumping chamber, the rotor body having projections that act as salient poles to interact with the rotating magnetic field, the rotor body also defining a plurality of hollows intermediate the projections, wherein the rotor body is mounted eccentrically with respect to the pumping chamber such that a gap between the rotor body and pumping chamber varies from a relatively wide portion to a relatively narrow portion, the gap being in fluid communication with the inlet and outlet; and

d) a plurality of cylindrical rollers disposed in the hollows for free radial movement within the hollows such that as the rotor body spins due to the rotating magnetic field, the widening gap draws fluid from the inlet and the narrowing gap expells the fluid from the outlet.

15. A vane pump assembly as recited in claim 1, wherein the roller seating deeper into the associated hollow provides a secondary pumping effect.

16. A vane pump assembly as recited in claim 1, further comprising a permanent magnet coupled to each projection.

17. A vane pump assembly as recited in claim 1, wherein the rotor body is a magnetic material.

18. A roller vane pump assembly comprising:

a) a stator assembly having a stator and windings for generating a rotating magnetic field;

b) a rotor assembly mounted for rotation about a rotor axis within a pumping chamber, the rotor assembly including a body having projections that act as salient poles to interact with the rotating magnetic field, the body also defining a plurality of hollows intermediate the projections, wherein the rotor assembly is mounted eccentrically with respect to the pumping chamber such that a plane substantially passing through the rotor and stator axis defines first and second sides of the body; and

c) a plurality of cylindrical rollers, each roller disposed in a respective hollow for free radial movement within the hollow,

wherein as the body spins due to the rotating magnetic field, volumes between adjacent rollers, the rotor assembly and the pumping chamber expand on the first side of the rotor drawing fluid from at least one inlet and contract on the second side expelling the fluid from at least one outlet.

19. A roller vane pump assembly as recited in claim 18, further comprising a housing defining the at least one inlet and the at least one outlet.